A new study says that Instagram is the worst social media network for young people's mental health, according to a new report by the Royal Society for Public Health in the U.K. And Snapchat is the second worst.

"FOMO" — aka the fear of missing out — may not be listed in the American Psychiatric Association's manual of mental disorders, but users who spent more than two hours a day on social media are more likely to report poor mental health and symptoms of anxiety and depression, says the study. Seeing endless pictures of friends on fun outings can also promote a "compare and despair" attitude among users, the report said.

The #StatusofMind survey asked nearly 1,500 people in the UK aged 14-24 to rate how social media platforms affected various aspects of their mental health.

Instagram got the worst scores, with the most negative marks coming for how the photo sharing platform hurt their body image and sleep, and increased instances of bullying and fear of missing out.

Snapchat had better scores in terms of loneliness, but was slightly worse in terms of sleep and FOMO.

It wasn't all "dislikes" though. All the services had good marks for self-expression and self-identity. And survey takers said they found emotional support and connected to online communities and support networks.

"With its almost universal reach and unprecedented ability to connect people from all walks of life, social media holds the potential to wield a mighty power as a positive catalyst for good mental health," the study's authors wrote.

"But there are also risks...which if not addressed and countered, can and have already opened the door for social media to cause significant problems for young people’s mental health and well-being."